The invention relates generally to heat transfer and power generation devices, and more particularly, to solid-state heat transfer devices.
Heat transfer devices may be used for a variety of heating/cooling and power generation/heat recovery systems, such as refrigeration, air conditioning, electronics cooling, industrial temperature control, waste heat recovery, and power generation. These heat transfer devices are also scalable to meet the thermal management needs of a particular system and environment. However, existing heat transfer devices, such as those relying on refrigeration cycles, are environmentally unfriendly, have limited lifetime, and are bulky due to mechanical components such as compressors and the use of refrigerants.
In contrast, solid-state heat transfer devices offer certain advantages, such as, high reliability, reduced size and weight, reduced noise, low maintenance, and a more environmentally friendly device. For example, thermoelectric devices transfer heat by flow of electrons and holes through pairs of p-type and n-type semiconductor thermoelements forming structures that are connected electrically in series and thermally in parallel. However, due to the relatively high cost and low efficiency of the existing thermoelectric devices, they are restricted to small scale applications, such as automotive seat coolers, generators in satellites and space probes, and for local heat management in electronic devices.
At a given operating temperature, the heat transfer efficiency of thermoelectric devices can be characterized by the figure-of-merit that depends on the Seebeck coefficient, electrical conductivity and the thermal conductivity of the thermoelectric materials employed for such devices. Many techniques have been used to increase the heat transfer efficiency of the thermoelectric devices through improving the figure-of-merit value. For example, in some heat transfer devices two-dimensional superlattice thermoelectric materials have been employed for increasing the figure-of-merit value of such devices. Such devices may require deposition of two-dimensional superlattice thermoelectric materials through techniques, such as molecular beam epitaxy or vapor phase deposition. However, such techniques are time consuming, are relatively expensive, are limited to small-scale applications, and require significant expertise.
Accordingly, there is a need to provide a thermal transfer device that has enhanced efficiency achieved through improved figure-of-merit of the thermal transfer device. It would also be advantageous to provide a device that is scalable to meet the thermal management needs of a particular system and environment.